1. Field of the Invention
The present invention relates to a method and apparatus for removing moisture from a compressed gas. In particular, the present invention relates to a method and apparatus for removing moisture from compressed air. Even more particularly, the present invention is related to a method and apparatus for removing moisture from compressed air which utilizes ambient temperature changes to provide coolant for removal of moisture from compressed air, and requires no external coolant source or energy source.
2. Description of the Related Art
Numerous devices are known in the art for removing moisture from (dehumidifying) compressed air. However, such devices require an external coolant or cooling process to be utilized in order to cool the compressed air sufficiently for the moisture to be removed from the air by condensation of the moisture. Coolants such as cold water, ice, and cold air sources have been utilized to cool compressed air to the point at which condensation occurs and moisture is removed from the compressed air. Hence, to provide such coolant sources and cooling processes requires the expenditure of energy. If ice is used to cool water, it is necessary to utilize energy to produce ice. If a conventional air conditioning system is used to provide coolant to cool the compressed air to promote condensation, energy is consumed by the refrigeration unit.
U.S. Pat. No. 3,910,062 discloses a dehumidifier having a tank containing a solution of cold water for cooling air passing through a tubular coil submerged in the tank so that the moisture content of the air is reduced. The water is cooled by adding ice thereto, or cold water from another source.
U.S. Pat. No. 3,942,330 discloses a method and apparatus for removing oil and water vapor from a compressed gas. The apparatus employs a vortex tube and a heat exchanger. The apparatus used in the method utilizes the energy in a portion of process gas.
U.S. Pat. No. 4,052,178 discloses a compressed air filter assembly utilized for centrifugally cooling and separating condensed moisture from compressed air and discharging clean air in the saturated condition at the outlet temperature and pressure. The air filter assembly utilizes the energy of the compressed gas by dropping the pressure of the gas in the filter to swirl the gas in a centrifugal manner through the filter to cool and remove moisture from the gas.
U.S. Pat. No. 4,242,110 discloses a drying apparatus for drying compressed air. The apparatus is a single vessel partitioned into various flow passages to direct the incoming water vapor bearing compressed gases through a heat exchanger, a refrigeration section, a de-mister, and then through a second heat exchanger for exit from the apparatus. Refrigeration coils are located in the space between the exterior casing and interior casing and lead to a suitable compressor-evaporator refrigeration system.
U.S. Pat. No. 4,237,796 discloses a compressed air system wherein the compressor receives air from the inlet cooler and dryer, compresses the air, and delivers it to a reheat air dryer where additional moisture is removed and the air is reheated. The chiller water line from the inlet cooler dryer passes through the reheat air dryer to remove additional moisture and back in the water chiller to form a closed cycle recycling water system.
U.S. Pat. No. 2,786,341 show a direct evaporative vortex refrigeration system in which a flow of gaseous fluid is cooled. The power source is a jet engine compressor which provides air under pressure. Water is injected into the compressed air to further cool the air.
Thus, the various gas drying apparatus and methods of the prior art require cooling units which require substantial amounts of external power in order to properly cool the gas to separate water therefrom, which results in higher energy costs. The method and apparatus of the present invention overcomes these problems by providing a method and apparatus which require no external power and no external water or coolant supply.